social/mass_mailing_partner/views/mail_mass_mailing_view.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright 2015 Pedro M. Baeza <pedro.baeza@tecnativa.com>
     Copyright 2015 Antonio Espinosa <antonio.espinosa@tecnativa.com>
     Copyright 2015 Javier Iniesta <javieria@antiun.com>
     License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html). -->
<odoo>

<record model="ir.ui.view" id="view_mail_mass_mailing_list_form">
    <field name="name">mail.mass_mailing.list.form</field>
    <field name="model">mail.mass_mailing.list</field>
    <field name="inherit_id" ref="mass_mailing.view_mail_mass_mailing_list_form"/>
    <field name="arch" type="xml">
        <xpath expr="//div[@class='oe_title']" position="after">
            <group>
                <group>
                    <field name="partner_mandatory"/>
                    <field name="partner_category"/>
                </group>
            </group>
        </xpath>
    </field>
</record>

</odoo>